Home Common Issues
This could be a sign of scale insert, which is fairly common for fern. You can usually wipe them off with a damp cloth and spray the foliage with insecticide afterward.
Plants that have been watered excessively can experience root rot and pathogen problems. Please check the soil and planter for proper drainage.
In most cases, this is likely caused by the lack of humidity and exposure to dry air. Move your plant to an area of the house with more humidity. You can also stand your plant in a humidity tray or use an electronic humidifier.
This can due to a number of factors. The plant might simply need fertilizer and/or has outgrown the pot if you have had it for a while. You can check for sign of pests or diseases and whether the soil is moist (but not soggy). You can ease the pot down to check the roots and make sure the plant is not severely pot bound (roots growing into the planter and there is little soil left).